Commutator.



J BURKE.

GOMMUTATOR. AYPLIOATION FILED DEC. 21, 1906.

Patented May 6, 1913.

5mm Mic-z U ITED STATES PATENT OFFICE.

JAMES BURKE, or EmnrENNsYLvANrA, ASSIGNOR T0 BURKE-ELECTRIC COMPANY,

. A CORPORATION or PENNSYLVANIA.

cbMMUTA'roR. I

Specificationof Letters Patent.

Patented May 6, 1913.

Application filed December 21, 1906. Serial No. 348,841.

To all whom; it may concern: n Be it known that I, JAMES BURKE, a'c1t1- zen of the United States, residing at Erie, in the county of Erie and Stateof Pennsylvania, have invented certain new and useful Improvements in Commutators, of which the following is a full, clear, and exact specification.

My invention relates to dynamo electric machines, and particularly to the construction of commutators or other c'urrent interrupting or circuit changing devices of simi lar character.

In the construction ,of commutators, it is the common practice to make the segments of copper on account of its good conductivity, toughness and other desirable properties. Each segment is made in one solid piece and as there must he means for clamping the segments to their support and also extensions for connecting the armature windin the size of each segment becomes consi erable. This amount of copper makes the total cost large. Moreover, it is cuss tomary to mill the extension of each seg-- ment, particularly on large machines, in order to provide a recess for the connection of the armature conductors. This increases the labor required and consequently the cost;

The object of my invention is to overcome these and other objections and at the same time preserve the advantages secured by the use 0 copper.

My invention will be understood from the following description and accompanying drawings, in which,

Figure 1 is a longitudinal section through a portion of a commutator embodying my invention; Fig. 2 is a"cross section on the line 22 of Fig. 1 showing a portion of the commutator segments; and Fig. 3 is a development of one of the enveloping stampings. In Fig. 1, the main cylindrical support is indicated at 1. This is shown as having an extension 2 and an undercut therein to receive and hold one end of each segment in place. At the opposite end of the segments,

an undercut ring 3 is fitted to the support- 1 and when forced up by the usualbolts as 4:, will hold the segments firmly in place.

: Each segment is a compositeone and comprises a'main portion 5 adapted to be en gaged by the parts 2, 3 and will preferably be made wedge shaped as shown in Fig. 2

and as is common in forming the solid cop:

per segments. Outside of the part 5 is an enveloping sheet of metal 6 which incloses the inner portion 5 of the sides and inner edge. This sheet 6 is provided with two extensions 7, 7, one from each side, and is adapted to receive between them conductors 8 from the armature windings which may be soldered in the usual'm'anner to secure good electrical contact. The inner portion 5 of each segment is preferably made of iron, or may be made of some other metal or composition which'is less expensive than copper. The enveloping sheet 6 is preferably made of copper, but may however, be made of other metals or compositions of relatively high conductivity compared with that of the inner portion. The enveloping part 6, may bemade from sheet metal and'stamped out to the form desired, such as shown in Fig. 3. The stamping will then be forced around the inner part so that in future handling and assembling, the composite segment' may be worked as a solid integralpiece. The engaging surfaces of the enve1-. oping stamping and body portion will preferably be tinned and-sweated together and so secure good electrical contact. After as-' sembling the segments with the usual in-- sulation. 9, the whole will be clamped together and the outer surface turned off smoothly inthe usual manner. In making connection to the armature conductors, it is slmp'ly necessary to secure the conductors-I between the two extensions 7.

By my invention, the conductivity'of the segment as a whole may be made ample,

and on account of the large surface contact and pressure between the copper and iron,

good electrical connection is secured, which may be improved if the copper and iron are tinned'and sweated together. account of the edges of the segment being made of copper, the segment will not deteriorate on account of sparking to the extent that it would-if made .wholly of iron.

This is important as it has beenshownin practice that segments made wholly of iron very rapidly roughen at the. edges and require constant attention and turning down..

With my improved construction, the iron is protected from sparking and consequently does not become rough from. thatcause.

While I have shown and described one Also on derstood that changes may be made in the form ofconstruction and in the materials used without departing from the scope thereof as indicated by the following claims. Having. thus described my invention,- I declare that What I claim as new and desire to secure by Letters Patent, is,

1. In a circuit changingdevice, a segment embodying an inner main portion containing iron and an outer portion of cop the' segment, said outer portion being formed of relatively thin copper embracing said inner main portion and adapted to be electrically connected to a conductor.

3. .In a commutator, a segment comprising an inner-main part of relatively long tread, and an outer part of relatively short tread serving as the trailing part of the segment, said outer part being of a material of relatively high conductivity and of relatively low corrodibilityas compared with the material of said inner main part, said outer part enveloping said inner main part and adapted tobe connected to a conductor.-

4. In a commutator, a segment comprising an inner main part containing iron and of relatively long tread and-an outer vpart of copper of relatively short tread serving as the trailing part of the segment, said trailing part enveloping said 111- ner main part and having extensions for electrical connection to a conductor.

5. In a circuit changing device, a segment embodying a main portion of iron-containing material, and a portion of copper disposed on the trailing side thereof, said copper portion being adapted to be connected to a conductor.

In testimony whereof I afiix my signa" ture, in presence of two witnesses.

JAMES BURKE.

\Vitnesses:

L. K. SAGER, GEO. N. KERR.

copies of this patent may be obtained for five centseach, by addressing the Commissioner of Patents,

Washington, D. G. 

